Sacrificial aluminum fins for failure mode protection of an aluminum heat exchanger

Abstract

A method of localized cathodic protection of a heat exchanger, includes providing at least one fin formed from a first metal alloy; applying a sacrificial layer of a second metal to at least one region in the at least one fin; and connecting a refrigerant tube to the at least one fin; wherein the sacrificial layer of the second metal includes a metal from one of a zinc alloy or a magnesium alloy.

The invention claimed is: 
     
       1. A heat exchanger exhibiting resistance to galvanic corrosion, comprising:
 a refrigerant tube; and 
 at least one fin formed from a first metal alloy, connected to the refrigerant tube along a fin surface portion in contact with the refrigerant tube; 
 said at least one fin including a sacrificial layer of a second metal disposed locally on at least one region in the at least one fin including on the fin surface portion in contact with the refrigerant tube and on a fin surface portion adjoining the fin surface portion in contact with the refrigerant tube; 
 wherein the sacrificial layer of the second metal includes a metal from one of a zinc or magnesium alloy. 
 
     
     
       2. The heat exchanger of  claim 1 , wherein the refrigerant tube is connected at a contact area within the at least one region. 
     
     
       3. The heat exchanger of  claim 1 , wherein the refrigerant tube is connected to a fin collar within the at least one region. 
     
     
       4. The heat exchanger of  claim 1 , wherein the refrigerant tube is at least formed from the first metal alloy of aluminum. 
     
     
       5. The heat exchanger of  claim 1 , wherein the first metal alloy is more noble than the second metal such that direct contact between the at least one fin and the refrigerant tube in the presence of an electrolyte would lead to galvanic corrosion of the sacrificial layer. 
     
     
       6. The heat exchanger of  claim 1 , wherein the sacrificial layer comprises one of a Zinc (Zn), Magnesium (Mg), or Beryllium (Be) based alloy clad to the at least one fin. 
     
     
       7. The heat exchanger of  claim 1 , wherein the sacrificial layer comprises a melted layer of the second metal sprayed onto the at least one fin or a vaporized form of the second metal deposited to the at least one fin. 
     
     
       8. The heat exchanger of  claim 1 , wherein the sacrificial layer on the fin surface portion adjoining the fin surface portion in contact with the refrigerant tube extends away from the refrigerant tube. 
     
     
       9. The heat exchanger of  claim 1 , wherein the sacrificial layer comprises an aluminum metal alloy formed with a 1 percent constituent of the second metal by weight. 
     
     
       10. A method of localized cathodic protection of the heat exchanger of  claim 1 , comprising:
 providing at least one fin formed from a first metal alloy; 
 applying a sacrificial layer of a second metal locally to at least one region in the at least one fin; and 
 connecting a refrigerant tube to a fin surface having the sacrificial layer thereon within the at least one region of the at least one fin bearing the sacrificial layer; 
 wherein the sacrificial layer of the second metal includes a metal from one of a zinc alloy or a magnesium alloy, and the tube is cathodic with respect to the fin. 
 
     
     
       11. The method of  claim 10 , wherein the connecting of the refrigerant tube further comprises connecting the refrigerant tube at a contact area within the at least one region. 
     
     
       12. The method of  claim 10 , wherein the connecting of the refrigerant tube further comprises connecting the refrigerant tube to a fin collar within the at least one region. 
     
     
       13. The method of  claim 10 , wherein the refrigerant tube is at least formed from the first metal alloy comprising aluminum. 
     
     
       14. The method of  claim 10 , wherein the first metal alloy is more noble than the second metal such that direct contact between the at least one fin and the refrigerant tube in the presence of an electrolyte would lead to galvanic corrosion of the sacrificial layer. 
     
     
       15. The method of  claim 10 , wherein the applying of the sacrificial layer further comprises cladding one of a Zinc (Zn), Magnesium (Mg), or Beryllium (Be) based alloy to the at least one fin. 
     
     
       16. The method of  claim 10 , wherein the applying of the sacrificial layer further comprises spraying a melted layer of the second metal to the at least one fin. 
     
     
       17. The method of  claim 10 , wherein the applying of the sacrificial layer further comprises depositing a vaporized form of the second metal to the at least one fin. 
     
     
       18. The method of  claim 1 , wherein the sacrificial layer applied on the fin surface portion adjoining the fin surface portion in contact with the refrigerant tube extends away from the refrigerant tube. 
     
     
       19. The method of  claim 10 , wherein the applying of the sacrificial layer further comprises applying a coating composition comprising powder of the second metal to the at least one fin. 
     
     
       20. The method of  claim 10 , wherein the applying of the sacrificial layer further comprises forming an aluminum metal alloy comprising a 0.5 to 2.5 percent constituent of the second metal by weight.